As described in U.S. Pat. No. 4,469,199, which is assigned to the same assignee as the present application, hydraulic elevator systems are normally controlled by indicia in the hatchway which cooperate with electrical switches carried by the elevator car. First and second vertical lanes of indicia, such as cams, establish slowdown distances relative to each floor, one for each travel direction, third and fourth vertical lanes of indicia alternately notch a floor selector, to eliminate false actuation of the selector due to contact bounce, and a fifth lane of indicia mount landing cams, which are also used when re-leveling is necessary. Each vertical lane of indicia requires a vertical tape in the hatchway which adds substantially to the initial cost of an elevator system, as well as to maintenance costs and thus it would be desirable and it is an object of the present invention, to reduce the number of such lanes.
The slowdown and landing indicia are used to control a hydraulic elevator valve, which typically includes up level, up stop, down level and down stop solenoids, as well as check and relief valves. The solenoids initiate preset speeds as the elevator car approaches and stops at a target floor. It would be desirable and is another object of the present invention to be able to control the speed, acceleration, and deceleration of a hydraulic elevator based upon car positional information which continuously indicates car position, without requiring tapes or other positional indicating devices in the hatchway.